The fastest marathon ever run on record was by Dennis Kimetto of Kenya in the 2014 Berlin marathon for a time of two hours, two minutes and 57 seconds. That means he ran an average pace of four minutes 41.4 seconds per mile over the entire 26.2-mile course. Kenyan runner Eliud Kipchoge and Ethiopian runner Guye Adola came very close to breaking this record at the Berlin marathon earlier this year.

While the fastest marathon time for men has been slowly but steadily improving for the last 30 years or so, the women’s record has held firm since 2003. Paula Radcliffe of Great Britain set the time to beat at two hours 15 minutes and 25 seconds (an average pace of five minutes 9.9 seconds per mile) in London over a decade ago.

Is there an absolute minimum time to run a marathon or will runners just keep getting faster? Will humans ever break the two hour mark? What does it take to set a world record marathon time? How does someone run a faster marathon?

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